Nherb Posted May 20, 2011 Report Share Posted May 20, 2011 Hi all, I need some help with my X-reg 3 series E46 318i. Bought it about a year ago now and strangely, after a couple of weeks driving round in it, the engine management light came on (I've heard a lot of different names for this light - so to clarify I've included a picture of the light that is on on my dashboard). Despite this light coming on there was no difference in the performance of the car at all. Natrually I took it back to the deaer who sold it to me - he arranged for it to go in to be looked at; they read the fault codes on a universal reader, which seemed to suggest there was some sort of air leak or faulty lambda. The mechanic couldn't find an air leak so changed lambdas and knocked the light off. I was very happy - until the light came back on about 3-4 days later. During that 3-4 days I had driven the car - a lot - so was a bit perplexed when it came back on. A few weeks later I was taking the car in to a BMW specialist for an MOT so I thought I'd get them to take a look whilst it was in there. They obliged and told me on my return that their BMW system had aknowledged that the light was on, but had read out 'no fault codes found'! I asked the guy what this meant at the time and he said he wasn't sure, but would suspect a small air leak as the culprit. He also said it wasn't a problem, and wasn't affecting the vehicle performance - so with that I decided to give up my hunt for what was causing the light. Since then I've had half of the engine out doing odd bits and bobs here and there, and whenever I have ben under the bonnet I've looked for an air leak. I must have been over the engine at least twice, but have never come across anything that I thought it may be! Absolutely no sign of an air leak anywhere at all! A month or so ago I thought I'd found the culprit - I noticed that when my MPG gauge on the dash started its sweep from left to right after taking off it made a hiss (sort of like a very quiet air leak), so figured it must be linked to that. Did a bit of digging around and saw that the vaccum line leading to the gauge sometimes rubs against the steering column and causes holes in the line. So set about taking mine apart to get at the steering column, but when I got in couldn't find a vaccum line... it must be electronically driven.... So have now discounted this theory! I'm really stuck - has anyone else had this problem, or know what the problem with mine might be?! Any help would be much appreciated! Cheers Nick Link to comment Share on other sites More sharing options...
jcjdavis1 Posted May 20, 2011 Report Share Posted May 20, 2011 Hi. Here are the hoses I had to replace on my 318i- http://www.realoem.com/bmw/showparts.do?model=AL32&mospid=47631&btnr=11_2071&hg=11&fg=45 1,3,5,and 15. 2 and 4 as well http://www.realoem.com/bmw/showparts.do?model=AL32&mospid=47631&btnr=11_1514&hg=11&fg=15 1 valve and 3 http://www.realoem.com/bmw/showparts.do?model=AL32&mospid=47631&btnr=11_1514&hg=11&fg=15 7x4 and 17 Plus have a read of this- http://forum.e46fanatics.com/showthread.php?t=827061&highlight=2000+e46+pipe+connector Jim Link to comment Share on other sites More sharing options...
TheBlackCats Posted May 20, 2011 Report Share Posted May 20, 2011 ive had EML light issues also on my 318i, ive replaced numerous hoses, replaced the crankcase vent valve and its hoses as the diaphram splits inside the housing, ive also cleaned MAF sensor, replaced the camshaft sensor, just been told today by BMW tech that the intake/manifold valve( EGR), might need cleaning as this can cause the EML to come on. its probably a case of elimanating one fault at a time, hope this helps Link to comment Share on other sites More sharing options...
s_spender Posted May 20, 2011 Report Share Posted May 20, 2011 how have you been looking for air leaks? Link to comment Share on other sites More sharing options...
Nherb Posted May 20, 2011 Author Report Share Posted May 20, 2011 Simply looking for perished tubes, any signs of tubes with holes in etc.... Any suggestions? Link to comment Share on other sites More sharing options...
jcjdavis1 Posted May 21, 2011 Report Share Posted May 21, 2011 Simply looking for perished tubes, any signs of tubes with holes in etc.... Any suggestions? Hi. Just replace them all, not to expensive from the Dealer, thats what I did. Jim Link to comment Share on other sites More sharing options...
s1monove Posted May 25, 2011 Report Share Posted May 25, 2011 Hi Mate, mine was doing this. The light was on for months and no fault codes were showing. I replaced the relevant sensors but still the light was on. It turned out, it was a leak on the lower intake hose (not sure what its called). After replacing this, all is now well. Touch wood!! Link to comment Share on other sites More sharing options...
s_spender Posted May 30, 2011 Report Share Posted May 30, 2011 get some brake cleaner and spray around the pipes etc, while engine is running any change in engine note will indicate you have found a leak. This isn't 100% fool proof but works on 95% of leaks. Link to comment Share on other sites More sharing options...
Nherb Posted June 22, 2011 Author Report Share Posted June 22, 2011 Further to this - does anyone know how the MPG gauge on the dash works? I have read different versions of this.... Link to comment Share on other sites More sharing options...
325coupe Posted June 22, 2011 Report Share Posted June 22, 2011 hi Buddy have you got any closer to fixing thi issue as sounds like the same we have had for a while, it gives up codes 143 & 147, was told it could be an air leak and to check hoses and have replaced most hoses under the bonnet now, on the topic of egr system is there a valve that can be cleaned ? Link to comment Share on other sites More sharing options...
Nherb Posted June 22, 2011 Author Report Share Posted June 22, 2011 Hi, I believe a bit closer to fixing this... touch wood! The garages that I have been to have always read out a code that they interpret to be a potential air leak - and as a result I've had half the engine out checking ALL the tubes for leaks etc but have never found anything remotely suspect! At the time I found it hard to believe it was an air leak as it has always seemed to be running a bit rich to me. Anyway, finally the other day I got so sick of the light being on I decided I'd invest in my own cheap diagnostic interface just to knock the light off. I bought an ELM327 scanner on eBay (£15) - Don't want to get drawn into a discussion re: peake vs ELM scanners. I am VERY happy with my ELM, cheap; does the job; and allows me to log data such as throttle position, air flow, fuel trims etc.... I would reccommend this. HOWEVER, I can see the advantages of a Peake - I would certainly buy this if I could afford this. Anyway, I got my scanner and stuck it on my 318i: error code read p0170 (fuel trim malfunction bank 1). And indeed having logged my fuel trim using my ELM I can see that the long term trims are at: 20.4 & 30.4 for banks 1 & 3 respectively - too high I believe?! I also noted that I had pending codes related to the MAF and the air intake temperature sensor. Having cleared these codes since, p0170 has resurfaced numerous times, but the pending ones have never been logged since. Having checked the air intake temp information the car is getting it doesn't seem that there is a fault with this sensor. Bit more tricky to check the MAF data though I guess. So suspect a bad/dirty MAF sensor at present. Am planning to clean my MAF in the next few days, so will let you know how that goes. Anybody else have any ideas regarding this in light of the new info? Thanks Link to comment Share on other sites More sharing options...
ohara Posted June 23, 2011 Report Share Posted June 23, 2011 we had the same light come on on my wife's Beetle we had it checked and faulty lambda sensor code was given. Both were changed and about three months later the light came back on , air flow sensor was next to be changed and once again the light came back on after a while. Next thing we checked all the vacuum pipe for a leak again. After that one one could suggest what it was.. This happened on and off over the three years we had the car (car was out of warranty and purchased privately), it always ran fine and never fail mot on emission or anything along those lines. After we changed the air flow meter I got fed up with throwing money at it and just left it on, when we came to sell the car it was sold with the light on. The buyer was the first person to look at the car and wasn't bothered by it at all. Had a friend with the same thing but with the airbag light kept throwing money at it but never fixed it. In the end because it was the airbag light he traded his car in. Link to comment Share on other sites More sharing options...
s_spender Posted June 23, 2011 Report Share Posted June 23, 2011 Can you get a live reading of the air mass of your scanner tool? If you can get someone to see what the max reading is when you are at max revs in 2nd gear but before rev limiter cuts in, let me know and we can compare this to a car without fault, out of interest have you changed/checked the crankcase breather valve? Link to comment Share on other sites More sharing options...
Nherb Posted June 23, 2011 Author Report Share Posted June 23, 2011 Thanks - that's most helpful! Just been out for a drive; under the conditions you describe it's reading 55.44g/s (that's 7.33lb/min). Sound right? Re: crankcase breather valve - checked and seems fine! Link to comment Share on other sites More sharing options...
Nherb Posted August 8, 2011 Author Report Share Posted August 8, 2011 Hi guys, Sorry to ressurect this thread, but thought I would let you know that I have now sorted my p0170 code! Turns out it was a lazy MAF sensor... As I was on a tight budget I didn't want to change this without being absolutely certain that it was the problem. I managed to diagnose the faulty MAF using my ELM327 scanner with scanXL software, which is able to record live data. I had thought that the MAF was ok in the past as it corresponded well with the engine RPM and I had given it a good clean. But after replacing crankcase breather and all associated tubing & checking entire intake tract for air leaks I turned my attention back to the MAF / fuel delivery system / pre-cat lambda. Although mine was a long-term fuel trim problem I used the short-term fuel trim readings to diagnose. I basically ran the car whilst recording throttle position & short-term fuel trims, expecting that the fuel trims should stay within +/-10%, they didn't! See the graph below... as I asked the car to go the lambda always seemed to ask for more petrol, yet it seemed fine at idle - figured it couldn't be an air leak then - progress! But, it have been MAF fuel delivery or a lazy lambda - so what I did was disconnect the MAF and then run the car under the same conditions again - this was conclusive; see below. A completely opposite trend. It had to be the MAF as the fuel trims under load were negative, the fuel system was delivering easily enough fuel, and the lambda was realising this fact. So I got myself down to Euro car parts, bought a Bosch MAF (they did me a deal for £160ish), stuck it in and recorded again.... see below - sorted! Checked my long-term fuel trim and it's back at zero for the first time in a year! Ver very happy indeed! I have read a lot of posts with people wanting to test their MAFs, but have never come across anyone suggesting how this can be done... Is this way a feasible way of doing so on the cheap? My scanner only cost me £15... reckon this could be quite helpful for a number of people! Link to comment Share on other sites More sharing options...
simonlpearce Posted August 8, 2011 Report Share Posted August 8, 2011 Some good diagnostics work you did there! Link to comment Share on other sites More sharing options...
tratante Posted May 14, 2013 Report Share Posted May 14, 2013 (edited) Hi, I got exactly the same problem in my e46... can someone tell me which PID i need to select to get that readings and where do i see the results after recording? I got the scan xl program but im struggling to do this test and i think the MAF in my car is dead too... I am actually seating in my car with laptop connected and any quick help would be apreciated... Thanks to all Edited May 14, 2013 by tratante Link to comment Share on other sites More sharing options...
tratante Posted May 14, 2013 Report Share Posted May 14, 2013 My car is a 1.9l E46 318i SE Touring 2001 model and the engine light is on for more than 1 year and i don't notice any problem with performance and its steady when idle. Also ive done 2 trips to portugal with the engine light on and i didnt had any problem apart from 32 MPG average i got in my car.... Link to comment Share on other sites More sharing options...
marc l Posted May 14, 2013 Report Share Posted May 14, 2013 32mpg is a bit low on a 1.9 (for motorway driving). But isn't that far off normal. Being quite a simple engine hopefully you'll be able to get to the bottom of this Link to comment Share on other sites More sharing options...
tratante Posted May 14, 2013 Report Share Posted May 14, 2013 32mpg is a bit low on a 1.9 (for motorway driving). But isn't that far off normal. Being quite a simple engine hopefully you'll be able to get to the bottom of this Thanks for you reply. I was getting about 38 Mpg before the engine light came on with the error p0170 bank trim 1... i checked for air leaks and i didn't noticed nothing and cleaned the Maf sensor but the problem still there.. Link to comment Share on other sites More sharing options...
Ginger Posted May 14, 2013 Report Share Posted May 14, 2013 if you haven't already checked the crankcase breather and associated pipe, do that first. If that proves to be ok, Check the disa flap which lives on the side of the inlet manifold. The diaphragm in it can split causing a mystery airleak. Link to comment Share on other sites More sharing options...
